Air conditioner outdoor unit and air conditioner

ABSTRACT

An air conditioner outdoor unit includes: a compressor; a heat source-side heat exchanger connected to the compressor; an oil separator disposed between a refrigerant discharge opening of the compressor and the heat source-side heat exchanger configured to separate a refrigerant oil from a refrigerant discharged from the compressor; and a first three-way valve fitted to a refrigerant pipe between the oil separator and the heat source-side heat exchange.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2013-032900 filed with the Japan Patent Office on Feb. 22, 2013, the entire content of which is hereby incorporated by reference.

BACKGROUND

1. Technical Field

The present disclosure relates to an air conditioner having an outdoor unit and an indoor unit, which are connected to each other through a plurality of refrigerant pipes.

2. Related Art

Conventionally, there is known an air conditioner having an outdoor unit and an indoor unit connected in parallel through a plurality of refrigerant pipes. In this air conditioner, a refrigerant circuit includes devices that are connected to refrigerant pipes by welding, and the refrigerant pipes themselves are also connected together by welding, and the refrigerant pipes are also connected to each other by welding. The refrigerant circuit is filled with a refrigerant.

The refrigerant circuit is connected to a compressor. The compressor compresses a low-pressure refrigerant suctioned in through a refrigerant suction opening into a high-pressure refrigerant, and discharges the high-pressure refrigerant through a refrigerant discharge opening. In case of failure, the compressor is detached from the refrigerant circuit for replacement. When the compressor is detached from the refrigerant circuit, the refrigerant filled in the refrigerant circuit should be prevented from escaping into the atmosphere. Thus, there is a need of recovering the refrigerant from the refrigerant circuit before the compressor is detached. However, recovering the refrigerant from the refrigerant circuit is a time consuming process. Particularly, for example, a multi-type an conditioner) in conditioner having a plurality of outdoor units and indoor units) installed in a building or housing complex has long refrigerant pipes and a large amount of refrigerant sealed in the refrigerant circuit. Thus, recovering the refrigerant from the refrigerant circuit is a time consuming process, resulting in poor maintainability of the air conditioner.

JP-A-7-332784 (Patent Document 1) proposes an air conditioner in which open/close valves are fitted to a discharge pipe (a refrigerant pipe connected to a refrigerant discharge opening) of a compressor and to an intake pipe (a refrigerant pipe connected to a refrigerant intake opening) of the compressor. The compressor of the air conditioner is detached from the refrigerant circuit after the open/close valves are closed. Thus, there is no need to recover the refrigerant from the refrigerant circuit. The air conditioner can be therefore maintained in a short time.

SUMMARY

An air conditioner outdoor unit includes: a compressor; a heat source-side heat exchanger connected to the compressor; an oil separator disposed between a refrigerant discharge opening of the compressor and the heat source-side heat exchanger configured to separate a refrigerant oil from a refrigerant discharged from the compressor; and a first three-way valve fitted to a refrigerant pipe between the oil separator and the heat source-side heat exchanger.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a refrigerant circuit of an air conditioner according to an embodiment of the present disclosure;

FIG. 2 is a diagram illustrating a refrigerant circuit of an outdoor unit of the air conditioner illustrated in FIG. 1, illustrating the detaching or attaching of the compressor; and

FIG. 3 is a diagram illustrating the refrigerant circuit of the outdoor unit of the an conditioner illustrated in FIG. 1 in a case where a first three-way valve fails.

DESCRIPTION OF EMBODIMENTS

In the following detailed description, for purpose of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.

The air conditioner described in Patent Document 1 includes an open/close valve fitted to the discharge pipe. This air conditioner is more likely to cause the following disadvantages than other air conditioners where the open/close valve is not fined to the discharge pipe. Namely, when the driving of the compressor causes vibration in the discharge pipe, a huge force may be applied to the discharge pipe and to a connection part between the discharge pipe and other devices (such as the compressor or an oil separator) due to the weight of the open/close valve. As a result, the discharge pipe and the connection part of the discharge pipe could be damaged. Generally, the discharge pipe of the compressor has a smaller pipe diameter than the intake pipe. Thus, the discharge pipe has a lower strength than the intake pipe. The open/close valves fitted to both the discharge pipe and the intake pipe increases the likelihood of damage to the discharge pipe due to vibrations is increased.

When the compressor is re-connected to the refrigerant circuit, the necessity may arise to vacuum the refrigerant circuit and perform refrigerant charging. In this case, for example, the amount of the refrigerant corresponds to the amount of refrigerant decreased by escaping into the air when the compressor is detached from or attached to the refrigerant circuit. Here, the term “refrigerant charging” used herein refers to injecting refrigerant into the refrigerant circuit. The air conditioner according to Patent Document 1 is additionally provided with a service valve, a branch pipe, and the like for vacuuming and refrigerant charging. However, such additional components may lead to increased costs and poor maintainability.

An object of the present disclosure is to provide an air conditioner with high compressor maintenance workability.

An air outdoor unit according to an embodiment of the present disclosure (the present outdoor unit) includes: a compressor; a heat source-side heat exchanger connected to the compressor; an oil separator disposed between a refrigerant discharge opening of the compressor and the heat source-side heat exchanger configured to separate a refrigerant oil from a refrigerant discharged from the compressor; and a first three-way valve fitted to a refrigerant pipe between the oil separator and the heat source-side heat exchanger.

The present outdoor unit may further include a flow path switching unit for switching the direction of flow of refrigerant in the heat source-side heat exchanger. The flow path switching unit may be disposed between the heat source-side heat exchanger and the oil separator, and the first three-way valve is disposed on a refrigerant pipe between the flow path switching unit and the oil separator.

In this case, the present outdoor unit may further include an oil return pipe with one end connected to the oil separator and the other end connected to a refrigerant pipe connected to a refrigerant intake opening of the compressor; and a second three-way valve disposed between a connection part of the refrigerant pipe and the oil return pipe, and the flow path switching unit.

Moreover, the first three-way valve may include a first port connected to the oil separator, a second port connected to the flow path switching unit, and a third port which is as service port. In addition, the second three-way valve may include a first port connected to the flow path switching unit, a second port connected to the refrigerant intake opening of the compressor, and a third port which is a service port.

In addition, an air conditioner according to an embodiment of the present disclosure includes the present outdoor unit, and an indoor unit connected to the outdoor unit.

In the present outdoor unit, the first three-way valve is disposed on a refrigerant pipe between the flow path switching unit and the oil separator. Thus, the force applied to the discharge pipe and to the connection part between the discharge pipe and the other devices is suppressed even when the discharge pipe is vibrated by the vibration of the compressor. As a result, damage to the discharge pipe and the connection part between the discharge pipe and the other devices is suppressed. Further, when re-attaching the detached compressor onto the refrigerant circuit, vacuuming can be performed through the vacant ports (the ports to which no refrigerant pipe is connected) of the first three-way valve and the second three-way valve. As a result, the cost increase due to separately fitting a service valve and a branch pipe can be suppressed, and high maintainability can be obtained.

In the following, an embodiment of the present disclosure will be described in detail with reference to the drawings. In an air conditioner according to the present embodiment, three indoor units are parallelly connected to one outdoor unit. The air conditioner can simultaneously perform cooling operation or heating operation in all of the indoor units. It should be noted that the present disclosure is not limited to the following embodiment, and various modifications can be made without departing from the gist of the disclosure.

As illustrated in FIG. 1, an air conditioner 1 according to the present embodiment includes one outdoor unit 2 installed outside a building o the like, and three indoor units 5 a to 5 c. The indoor units 5 a to 5 c are connected to the outdoor unit 2 in parallel through a liquid pipe (refrigerant pipe) 8 and a gas pipe (refrigerant pipe) 9. Specifically, one end of the liquid pipe 8 is connected to an operating valve 27 of the outdoor unit 2. The other end of the liquid pipe 8 is branched and respectively connected to closing valves 53 a to 53 c of the indoor units 5 a to 5 c. One end of the gas pipe 9 is connected to an operating valve 28 of the outdoor unit 2. The other end of the gas pipe 9 is branched and connected to closing valves 54 a to 54 c of the indoor units 5 a to 5 c, respectively. Thus, a refrigerant circuit 100 of the air conditioner 1 is formed.

The outdoor unit 2 will be described. The outdoor unit 2 includes a compressor 21, a four-way valve (flow path switching unit) 22, an outdoor heat exchanger (heat source-side heat exchanger) 23, an oil separator 24, an outdoor expansion valve 25, the operating valve 27 to which one end of the liquid pipe 8 is connected, the operating valve 28 to which one end of the gas pipe is connected a first three-way valve 11, a second three-way valve 12, and an outdoor fan 29. The above members except for the outdoor fan 29 are mutually connected through refrigerant pipes described below. Thus, an outdoor unit refrigerant circuit 20 as part of the refrigerant circuit 100 is formed.

The compressor 21 is driven by a motor (not shown) whose rotational speed is control by an inverter. Namely, the compressor 21 is a capacity-variable compressor capable of varying operation capacity. A refrigerant discharge side of the compressor 21 is connected to a refrigerant inflow side of the oil separator 24 through a discharge pipe 41. A refrigerant intake side of the compressor 21 is connected to the four-way valve 22 (described later) through an intake pipe 42.

The four-way valve 22 is a valve for switching the direction of flow of refrigerant, and includes four ports a, b, c, and d. The port a is connected to a refrigerant outflow side of the oil separator 24 through an outflow pipe 43. The port b is connected to one refrigerant entry/exit opening of the outdoor heat exchanger 23 through a refrigerant pipe 44. The port c is connected to the refrigerant intake side of the compressor 21 through the intake pipe 42. The port d is connected to the operating valve 28 through an outdoor unit gas pipe 46. Thus, the four-way valve 22 is configured to switch the refrigerant flow path between the outdoor heat exchanger 23, the oil separator 24, the compressor 21 and the operating valve 28.

The four-way valve 22 switches the direction of refrigerant of the outdoor heat exchanger 23. As illustrated in FIG. 1, when the ports a and h of the four-way valve 22 make communication with each other, the refrigerant flows from the refrigerant temperature sensor 35 to the refrigerant temperature sensor 36 through the heat source-side heat exchanger 23 (during cooling operation). On the other hand, the ports b and c of the four-way valve 22 make communication with each other, the refrigerant flows from the refrigerant temperature sensor 36 to the refrigerant temperature sensor 35 through the heat source-side heat exchanger 23 (during heating operation). Thus, the four-way valve 22 serves as a flow path switching unit for switching the direction of flow of the refrigerator in the heat source-side heat exchanger.

The outdoor heat exchanger 23 carries out heat exchange between the refrigerant and outer air taken into the outdoor unit 2 by the outdoor fan 29 (as will be described below). The one refrigerant entry/exit opening of the outdoor heat exchanger 23 is connected to the port b of the four-way valve 22, as described above. The other refrigerant entry/exit opening of the outdoor heat exchanger 23 is connected to the operating valve 27 through an outdoor unit liquid pipe 45.

The outdoor expansion valve 25 is an electronic expansion valve fitted to the outdoor unit liquid pipe 45. By adjusting the opening degree of the outdoor expansion valve 25, the amount of refrigerant that flows into the outdoor heat exchanger 23, or the amount of refrigerant that flows out of the outdoor heat exchanger 23 can be adjusted.

The oil separator 24 is fixed on a casing of the outdoor unit 2 by metal fittings and the like (not shown). As described above, the refrigerant inflow side of the oil separator 24 is connected to the refrigerant discharge opening of the compressor 21 through the discharge pipe 41. The refrigerant outflow side of the oil separator 24 is connected to the port a of the four-way valve 22 through the outflow pipe 43. The oil separator 24 separates refrigerant oil for the compressor 21 contained in the refrigerant discharged out of the compressor 21 from the refrigerant. The separated refrigerant oil is suctioned into the compressor 21 through an oil return pipe 47 (as will be described below).

The oil return pipe 47 has an end connected to an oil return opening of the oil separator 24 and the other end connected to the intake pipe 42. The oil return pipe 47 is provided with a capillary tube 26.

The first three-way valve 11 is disposed on the outflow pipe 43. The first three-way valve 11 includes three ports e, f, and g. The port e (a first port of the first three-way valve) is connected to the refrigerant outflow side of the oil separator 24. The port f (a second port of the first three-way valve) is connected to the port a of the four-way valve 22. The port g (a third port of the first three-way valve) is a service port for vacuuming and the like of the refrigerant pipe. The first three-way valve 11 can be switched to make communication at least between the ports e and f, or between the ports e and g.

The second three-way valve 12 is disposed on the intake pipe 42. More specifically, the second three-way valve 12 is disposed on the four-way valve 22 side with respect to the point of connection of the oil return pipe 47 and the intake pipe 42. The second three-way valve 12 includes three ports h, j, and k. The port h (a first port of the second three-way valve) is connected to the port c of the four-way valve 22. The port j (a second port of the second three-way valve) is connected to the refrigerant intake side of the compressor 21. The port k (a third port of the second three-way valve) is a service port for vacuuming and the like of the refrigerant pipes. The second three-way valve 12 can be switched to make communication at least between the ports h and j, or between the ports j and k.

The outdoor fan 29 is formed of a resin material and is disposed in the vicinity of the outdoor heat exchanger 23. The outdoor fan 29 is rotated by the fan motor (not shown). Thus, the outer air is taken into the outdoor unit 2, and the outer air that exchanges heat with the refrigerant in the outdoor beat exchanger 23 is released from the outdoor unit 2.

Other than the configuration described above, the outdoor unit 2 is provided with various sensors. As illustrated in FIG. 1, the discharge pipe 41 is provided with a high pressure sensor 31 and a discharge temperature sensor 33. The high pressure sensor 31 detects the pressure of the refrigerant discharged out of the compressor 21. The discharge temperature sensor 33 detects the temperature of the refrigerant discharged out of the compressor 21. The intake pipe 42 is provided with a low-pressure sensor 32 and an intake temperature sensor 34 in the vicinity of the refrigerant intake side of the compressor 21. The low-pressure sensor 32 detects the pressure of the refrigerant suctioned into the compressor 21. The intake temperature sensor 34 detects the temperature of the refrigerant suctioned into the compressor 21.

Between the four-way valve 22 and the outdoor heat exchanger 23, the refrigerant pipe 44 is provided with a refrigerant temperature sensor 35. The refrigerant temperature sensor 35 detects the temperature of the refrigerant that flows into the outdoor heat exchanger 23, or the temperature of the refrigerant that flows out of the outdoor heat exchanger 23. Between the outdoor heat exchanger 23 and the outdoor expansion valve 25, the outdoor unit liquid pipe 45 is provided with a refrigerant temperature sensor 36. The refrigerant temperature sensor 36 detects the temperature of the refrigerant that flows out of the outdoor heat exchanger 23, or the temperature of the refrigerant that flows into the outdoor heat exchanger 23. In the vicinity of the suction opening (not shown) of the outdoor unit 2, an outer air temperature sensor 37 is provided. The outer air temperature sensor 37 detects the temperature of the outer air that flows into the outdoor unit 2, i.e., the outer air temperature.

Next, the three indoor units 5 a to 5 c will be described. The three indoor units 5 a to 5 c are provided with indoor heat exchangers 51 a to 51 c (user-side heat exchangers), indoor expansion valves 52 a to 52 c, the closing valves 53 a to 53 c, the closing valves 54 a to 54 c, and indoor fans 55 a to 55 c, respectively. The indoor expansion valves 52 a to 52 c are indoor refrigerant flow rate adjuster. The closing valves 53 a to 51 c are connected to the other end of the branched liquid pipe 8. The closing valves 54 a to 54 c are connected to the other end of the branched gas pipe 9. These members except for the indoor fans 55 a to 55 c are mutually connected through refrigerant pipes, as will be described below. Thus, indoor unit refrigerant circuits 50 a to 50 c as part of the refrigerant circuit 100 are formed.

The indoor units 5 a to 5 c have identical configurations. Thus, in the following description, the configuration of the indoor unit 5 a will be described, and the description of the other indoor units 5 b and 5 c will be omitted. In FIG. 1, the members of the indoor unit 5 b corresponding to the members of the indoor unit 5 a are designated with the signs for the members of the indoor unit 5 a with the “a” at the end replaced with “b”. Similarly, the members of the indoor unit 5 c corresponding to the members of the indoor unit 5 a are designated with the signs for the member of the indoor unit 5 a with the “a” at the end replaced with “c”.

The indoor heat exchanger 51 a carries out heat exchange between the refrigerant and the indoor air taken into the indoor unit 5 a by an indoor fan 55 a (as will be described below). One refrigerant entry/exit opening of the indoor heat exchanger 51 a is connected to the dosing valve 53 a through an indoor unit liquid pipe 71 a. The other refrigerant entry/exit opening of the indoor heat exchanger 51 a is connected to the closing valve 54 a through an indoor unit gas pipe 72 a. The indoor heat exchanger 51 a functions as an evaporator when the indoor unit 5 a performs cooling operation. The indoor heat exchanger 51 a functions as a condenser when the indoor unit 5 a performs heating operation.

The indoor expansion valve 52 a is an electronic expansion valve fitted to the indoor unit liquid pipe 71 a. The opening degree of the indoor expansion valve 52 a is adjusted based on the required cooling capacity when the indoor heat exchanger 51 a functions as an evaporator. Similarly, the opening degree of the indoor expansion valve 52 a is adjusted based on the required heating capacity when the indoor heat exchanger 51 a functions as a condenser.

The indoor fan 55 a is formed of a resin material and is disposed in the vicinity of the indoor heat exchanger 51 a. The indoor fan 55 a is rotated by a fan motor (not shown). Thus, the indoor air is taken into the indoor unit 5 a. Then, the indoor air exchanges beat with the refrigerant in the indoor heat exchanger 51 a, followed by being supplied to the indoor space.

Other than the configuration described above, the indoor unit 5 a is provided with various sensors. The indoor unit liquid pipe 71 a is provided with a liquid-side temperature sensor 61 a between the indoor heat exchanger 51 a and the indoor expansion valve 52 a. The liquid-side temperature sensor 61 a is a heat exchanger entry temperature detector that detects the temperature of the refrigerant that flows into the indoor heat exchanger 51 a, or the temperature of the refrigerant that flows out of the indoor heat exchanger 51 a. The indoor unit gas pipe 72 a is provided with to gas-side temperature sensor 62 a. The gas-side temperature sensor 62 a detects the temperature of the refrigerant that flows out of the indoor heat exchanger 51 a, or the temperature of the refrigerant that flows into the indoor heat exchanger 51 a. In the vicinity of the indoor air suction opening (not shown) of the indoor unit 5 a, an indoor temperature sensor 63 a is provided. The indoor temperature sensor 63 a is an indoor temperature detector that detects the temperature of the indoor air that flows into the indoor unit 5 a, the indoor temperature.

Next, the flow of refrigerant and the operation of each member in the refrigerant circuit 100 of the air conditioner 1 according to the present embodiment during an air-conditioning operation will be described with reference to FIG. 1. In the following description, an example in which the indoor units 5 a to 5 c perform cooling operation will be described. A detailed description of an example in which the indoor units 5 a to 5 c perform heating operation will be omitted. The arrows in FIG. 1 indicate the flow of refrigerant during cooling operation.

As illustrated in FIG. 1, when the indoor units 5 a to 5 c perform cooling operation, the four-way valve 22 of the outdoor unit 2 is switched to make communication between the ports a and b, and between the ports c and d. The communication between the ports is indicated in FIG. 1 by solid lines. Thus, the outdoor heat exchanger 23 functions as a condenser, while the indoor heat exchangers 51 a to 51 c function as evaporators.

The high-pressure refrigerant discharged out of the compressor 21 flows through the discharge pipe 41 and the oil separator 24 into the outflow pipe 43. The refrigerant flows into the four-way valve 22, and then flows out of the four-way valve 22 and into the outdoor heat exchanger 23 through the refrigerant pipe 44. The refrigerant that flows into the outdoor heat exchanger 23 exchanges heat with the outer air taken into the outdoor unit 2 by the rotation of the outdoor fan 29, whereby the refrigerant is condensed. The refrigerant flows out of the outdoor heat exchanger 23 and then flows through the outdoor unit liquid pipe 45, followed by flowing into the liquid pipe 8 through both the fully opened outdoor expansion valve 25 and the fully opened operating valve 27.

The refrigerant that flows through the liquid pipe 8 is branched and flows into the indoor units 5 a to 5 c through the closing valves 53 a to 53 c, respectively. The refrigerant flows through the indoor unit liquid pipes 71 a to 71 c, and is depressurized into low-pressure refrigerant when the refrigerant passes the indoor expansion valves 52 a to 52 c. The refrigerant that flows into the indoor heat exchangers 51 a to 51 c through the indoor unit liquid pipes 71 a to 71 c exchanges heat with the indoor air taken into the indoor units 5 a to 5 c by the rotation of the indoor fans 55 a to 55 c, whereby the refrigerant is evaporated. Thus, the indoor heat exchangers 51 a to 51 c function as evaporators, and the indoor air that exchanges heat with the refrigerant in the indoor heat exchangers 51 a to 51 c is blown indoor out of an outlet (not shown). In this way, the air of the indoor spaces in which the indoor units 5 a to 5 c are installed is cooled.

The refrigerant that flows out of the indoor heat exchangers 51 a to 51 c flows through the indoor unit gas pipes 72 a to 72 c and into the gas pipe 9 through the closing valves 54 a to 54 c. The refrigerant flows through the gas pipe 9 and into the outdoor unit 2 through the operating valve 28. The refrigerant then flows through the outdoor unit gas pipe 46, the four-way valve 22, and the intake pipe 42, and is suctioned into the compressor 21 where the refrigerant is compressed again.

As described above, the refrigerant is circulated through the refrigerant circuit 100 as the air conditioner 1 performs cooling operation.

When the indoor units 5 a to 5 c perform heating operation, the four-way valve 22 of the outdoor unit 2 is switched to make communication between the ports a and d. The four-way valve 22 is also switched to make communication between the ports b and c. In FIG. 1, the communication between the ports is indicated by broken lines. Thus, the outdoor heat exchanger 23 functions as an evaporator, while the indoor heat exchangers 51 a to 51 c function as condensers.

With reference to FIGS. 1 and 2, the effect of disposing the first three-way valve 11 and the second three-way valve 12 in the air conditioner 1 will be described.

First, with reference to FIG. 1 the effect of the first three-way valve 11 disposed on the outflow pipe 43 will be described. The compressor 21 is driven at a predetermined rotational speed when the air conditioner 1 is performing air-conditioning operation. Vibrations caused by the rotation of the compressor 21 are also transmitted to the discharge pipe 41 connected to the refrigerant discharge opening of the compressor 21.

If the first three-way valve 11 is fitted to the discharge pipe 41, when the discharge pipe 41 vibrates due to the driving of the compressor 21, a large three may be applied to the body of the discharge pipe 41, the connection part between the discharge pipe 41 and the compressor 21 on the refrigerant discharge side), and the connection part between the discharge pipe 41 and the oil separator 24 on the refrigerant inflow side), due to the weight of the first three-way valve 11. As a result, the discharge pipe 41 and the above connection parts may be damaged.

However, as illustrated in FIG. 1, the first three-way valve 11 of the air conditioner 1 according to the present embodiment is disposed on the outflow pipe 43. Thus, even if the discharge pipe 41 vibrates due to the driving of the compressor 21, the force applied to the discharge pipe 41 and the connection parts between the discharge pipe 41 and the other devices is decreased compared with the ease where the first three-way valve 11 is fitted to the discharge pipe 41, whereby the damage to these parts can be suppressed. Further, as described above, the oil separator 24 is fixed to the casing of the outdoor unit 2 using metal fittings and the like. Thus, the occurrence of vibrations in the oil separator 24 due to the driving of the compressor 21 can be suppressed. Moreover, the vibration of the outflow pipe 43 connected to the oil separator 24 can be suppressed. Therefore, due to the weight of the first three-way valve 11 fitted to the outflow pipe 43, application of a large three to the outflow pipe 43 and the connection parts between the outflow pipe 43 and other devices can be also suppressed. As a result, damage to the outflow pipe 43 and the above-mentioned connection parts can be also suppressed.

Next, with reference to FIGS. 1 and 2, the states of communication in the first three-way valve 11 and the second three-way valve 12 when the compressor 21 is detached from the outdoor unit refrigerant circuit 20, and when the compressor 21 is re-attached to the outdoor unit refrigerant circuit 20, and their effect will he described.

The case where the compressor 21 is detached from the outdoor unit refrigerant circuit 20 will he described. First, a suction hose (not shown) of a refrigerant recovery machine is connected to the port g of the first three-way valve 11. Then, as illustrated in FIG. 2, when the compressor 21 is detached from the refrigerant circuit, the first three-way valve 11 is switched to make communication between the ports e and g, while the second three-way valve 12 is switched to make communication between the ports j and k. Thus, a part between the port e of the first three-way valve 11 and the port j of the second three-way valve 12 (hereafter referred to as a separated refrigerant circuit) is cut off from the outdoor unit refrigerant circuit 20.

Next, the refrigerant recovery machine is driven to recover the refrigerant remaining in the separated refrigerant circuit. Thus, the amount of refrigerant that needs to be recovered can be decreased compared with the case where, for example, the refrigerant is recovered from the refrigerant circuit of the outdoor unit 2 as a whole by using the service ports (the blacked-out ports in FIG. 1) of the operating valve 27 and the operating valve 28. Thus, the time required for refrigerant recovery can be decreased. Preferably, the suction hose of the refrigerant recovery machine may be connected to the port k of the second three-way valve 12 to recover the remaining refrigerant in the separated refrigerant circuit.

After the refrigerant recovery from the separated refrigerant circuit is completed, the compressor 21 is separated from the discharge pipe 41 and the intake pipe 42 and is thus detached. Thereafter, the detached compressor 21 is maintained and attached to the outdoor unit refrigerator circuit 20. Alternatively, a new compressor 21 is attached to the outdoor unit refrigerant circuit 20.

When the compressor 21 is attached to the outdoor unit refrigerant circuit 20, the discharge pipe 41 is connected to the refrigerant discharge opening of the compressor 21 and welded, while the intake pipe 42 is connected to the refrigerant intake opening of the compressor 21 and welded. After the welding is completed, a vacuum pump (not shown) is connected to the port g of the first three-way valve 11 to vacuum the separated refrigerant circuit. In this case, too, the amount of air that needs to be removed can be decreased compared with the case where, for example, the refrigerant circuit of the outdoor unit 2 as a whole is vacuumed by using the service ports of the operating valve 27 and the operating valve 28. Thus, the time required for vacuuming can be decreased. Preferably, the yarn tun pump may be connected to the port k of the second three-way valve 12 to vacuum the separated refrigerant circuit.

After the vacuuming of the separated refrigerant circuit is completed, a tank with refrigerant sealed therein (not shown; hereafter referred to as a refrigerant tank) is connected to the service port of the operating valve 27. In the refrigerant tank, an amount of refrigerant sufficient for filling the amount of refrigerant recovered from the separated refrigerant circuit at the time of detaching the compressor 21 is sealed. By connecting the refrigerant tank to the service port of the operating valve 27, the refrigerant flows from the high-pressure refrigerant tank into the outdoor unit liquid pipe 45 and the liquid pipe 8. Thus, the refrigerant is charged in the refrigerant circuit 100. The amount of refrigerant charged is no more than the amount of refrigerant recovered from the separated refrigerant circuit when the compressor 21 is detached. Thus, the time required for refrigerant charging can be decreased.

After the charging of refrigerant into the refrigerant circuit 100 is completed, the refrigerant tank is detached from the service port of the operating valve 27. Then, the second three-way valve 12 is switched to make communication between the ports h and j, whereby the pressures in the ports h and j are made even (equalized). Then, the first three-way valve 11 is switched, to make communication between the ports e and f. In this way, the attaching of the compressor 21 onto the refrigerant circuit is completed.

As described above, in the air conditioner 1, the first three-way valve 11 and the second three-way valve 12 are operated when the compressor 21 is detached from the outdoor unit refrigerant circuit 20, and when the compressor 21 is re-attached to the outdoor unit refrigerant circuit 20. Thus, the time required for refrigerant recovery when detaching the compressor 21, and the time for vacuuming and refrigerant charging when attaching the compressor 21 can be significantly decreased. Thus, the maintainability of the air conditioner 1 is improved.

With reference to FIGS. 1 and 3, the effect of the second three-way valve 12 disposed on the four-way valve 22 side of the intake pipe 42 with resect to the point of connection of the oil return pipe 47 and the intake pipe 42, in addition to the first three-way valve 11 disposed on the outflow pipe 43, will be described.

As illustrated in FIG. 3, in case that when the air conditioner 1 is performing, air-conditioning operation, namely, when the compressor 21 is being driven, the first three-way valve 11 fails and is fixed in a closed state, then the refrigerant discharged out of the compressor 21 flows through the discharge pipe 41 into the oil separator 24, and then flows out of the oil separator 24 into the oil return pipe 47. The refrigerant then flows into the intake pipe 42 through the capillary tube 26, flows through the intake pipe 42, and is then suctioned into the compressor 21.

If the first three-way valve 11 is fitted to the discharge pipe 41, when the first three-way valve 11 fails and is fixed in the closed state, the refrigerant discharged out of the compressor 21 is blocked b the first three-way valve 11. If the compressor 21 continues to be driven in this state, the compressor 21 may fail.

In case that when the second three-way valve 12 is disposed on the compressor 21 side of the intake pipe 42 with respect to the point of connection of the oil return pipe 47 and the intake pipe 42 the second three-way valve 12 fails and is in a closed state, then the refrigerant that flows out of the oil return pipe 47 into the intake pipe 42 is blocked by the second three-way valve 12. In this case, the refrigerant cannot be suctioned in, and the compressor 21 may be damaged.

However, according to the present embodiment, as illustrated in FIGS. 1 and 3, the first three-way valve 11 is disposed on the outflow pipe and the second three-way valve 12 is disposed on the four-way valve 22 side of the intake pipe 42 with respect to the point of connection of the oil return pipe 47 and the intake pipe 42. Thus, the refrigerant discharged out of the compressor 21 flows through the discharge pipe 41, the oil separator 24, the oil return pipe 47, and the intake pipe 42 successively, and is then suctioned into the compressor 21. As a result, even when the first three-way valve 11 and/or the second three-way valve 12 fails and is placed in the dosed state, damage to the compressor 21 can be suppressed.

However, if the driving of the compressor 21 continues while the first three-way valve 11 and/or the second three-way valve 12 is closed, the discharge pressure of the compressor 21 may be increased beyond an upper-limit value. Thus, a threshold value may be set lower than the upper-limit value of the discharge pressure of the compressor 21 by a predetermined value. Then, high pressure protection control such that the compressor 21 stops when the discharge pressure of the compressor 21 reaches the threshold value may be implemented. The discharge pressure of the compressor 21 is detected by the high pressure sensor 31.

As described above, in the air conditioner according to the present disclosure, the first three-way valve 11 is disposed on the outflow pipe 43, with one end of the outflow pipe 43 connected to the oil separator 24 fixed onto the casing of the outdoor unit 2. Thus, the discharge pipe 41 and the outflow pipe 43 can be suppressed from greatly vibrating due to vibration of the compressor 21. Thus, damage to the discharge pipe 41 and the connection parts between the discharge pipe 41 and the other devices due to vibrations can be suppressed. Further, damage to the outflow pipe 43 and the connection parts between the outflow pipe 43 and the other devices due to vibrations can be suppressed.

When the compressor is attached to the refrigerant circuit, vacuuming can be performed from the vacant port of the first three-way valve or the second three-way valve (i.e., the port to which no refrigerant pipe is connected). Thus, the cost increase due to separately fining the service valve and/or the branch pipe can be limited, whereby the time required for vacuuming can be decreased.

The embodiment has been described above with reference to the example of the air conditioner in which a plurality (three) of indoor units is connected to one outdoor unit through refrigerant pipes. However, the air conditioner according to the embodiment of the present disclosure is not limited to such a configuration. For example, the air conditioner according to the embodiment of the present disclosure includes an air conditioner in which one outdoor unit and one indoor unit are connected through refrigerant pipes, and an air conditioner in which a plurality of outdoor units and a plurality of indoor units are connected through refrigerant pipes.

The air conditioner according to the present disclosure may be expressed as a first air conditioner and a second air conditioner as follows.

The first air conditioner includes a refrigerant circuit including a compressor, a flow path switcher, a heat source-side heat exchanger, at least one expansion valve, and a user-side heat exchanger which are connected through a refrigerant pipe; an oil separator disposed between the compressor and the heat source-side heat exchanger configured to separate a refrigerant oil from a refrigerant discharged from the compressor; an oil return pipe with one end connected to the oil separator and the other end connected to an intake pipe which is a part of a refrigerant pipe connecting a refrigerant: intake opening of the compressor and the flow path switcher, and having a capillary tube; and a first three-way valve disposed on an outflow pipe which is a part of a refrigerant pipe connected to a refrigerant outflow opening of the oil separator.

The second air conditioner is the first air conditioner further including a second three-way valve fitted to the intake pipe and disposed between as connection part of the oil return pipe to the intake pipe and the flow path switcher.

According to the above air conditioners, because the first three-way valve is disposed on the outflow pipe, a large force is not applied to the discharge pipe and the connection part between the discharge pipe and other devices even when the discharge pipe is vibrated by the vibration of the compressor, so that the discharge pipe and the connection part between the discharge pipe and the other devices are not damaged. Further, when re-attaching the detached compressor onto the refrigerant circuit, vacuuming can be performed through a vacant port of the first three-way valve and the second three-way valve (the port to which the refrigerant pipe is not connected), whereby the cost increase due to the fitting of separate service valve or branch pipe can be avoided, and high maintainability can be obtained.

The foregoing detailed description has been presented for the purposes of illustration and description. Many modifications and variations are possible in light of the above teaching. It is not intended to be exhaustive or to limit the subject matter described herein to the precise form disclosed. Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims appended hereto. 

What is claimed is:
 1. An air conditioner outdoor unit comprising: a compressor; a heat source-side heat exchanger connected to the compressor; an oil separator disposed between a refrigerant discharge opening of the compressor and the heat source-side heat exchanger configured to separate a refrigerant oil from a refrigerant discharged from the compressor; and a first three-way valve fitted to a refrigerant pipe between the oil separator and the heat source-side heat exchanger.
 2. The air conditioner outdoor unit according to claim 1, further comprising a flow path switching unit for switching the direction of flow of refrigerant in the heat source-side heat exchanger, wherein: the flow path switching unit disposed between the heat source-side heat exchanger and the oil separator; and the first three-way valve is disposed on a refrigerant pipe between the flow path switching unit and the oil separator.
 3. The air conditioner outdoor unit according to claim 2, further comprising: an oil retrain pipe with one end connected to the oil separator and the other end connected to a refrigerant pipe connected to a refrigerant intake opening of the compressor; and a second three-way valve disposed between a connection part of the refrigerant pipe and the oil return pipe, and the flow path switching unit.
 4. The air conditioner outdoor unit according to claim 3, wherein: the first three-way valve includes a first port connected to the oil separator, a second port connected to the flow path switching unit, and a third port which is a service port; and the second three-way valve includes a first port connected to the flow path switching unit, a second port connected to the refrigerant intake opening of the compressor, and a third port which is a service port.
 5. An air conditioner comprising: the outdoor unit according to claim 1; and an indoor unit connected to the outdoor unit. 